1. Technical Field of the Invention
The present invention relates to a flexible wiring board and, more particularly, to a flexible wiring board for connecting therethrough a suspension substrate for mounting thereon a magnetic head of a hard disk drive and a control circuit substrate for actuating the magnetic head.
2. Description of the Prior Art
A readable and writable magnetic head is mounted on the hard disk drive used as a magnetic storage device of a computer. For example, a MR head (a magneto resistive head) and the like are being used as the magnetic head. With further increased speedup, high-density and high-capacity being increasingly desired for the hard disk drive in these years, the use of a thinner and higher density GMR head (giant magneto resistive head) is being anticipated.
Illustrated in FIG. 7 is a principal structure of the hard disk drive mounting this magnetic head thereon. In FIG. 7, the hard disk drive 1 comprises a magnetic disk 2 that rotates at high velocity revolution, a magnetic head 3 disposed in opposition to the magnetic disk 2, a suspension substrate 4 on which the magnetic head 3 is mounted, a carriage 5 on which the suspension substrate 4 is mounted, a control circuit substrate 6, located near the carriage 5, for actuating the magnetic head 3, and a flexible wiring board 7 mounted on the carriage 5 to extend along the longitudinal direction thereof
The suspension substrate 4, which is formed of a resilient board of e.g. stainless steel, has thereon a predetermined circuit pattern to be connected with the magnetic head 3 and carries thereon the magnetic head 3 with a very small gap kept against the magnetic disk 2.
The carriage 5 is attached to the suspension substrate 4 at the tip end portion thereof and is rotatably supported at the base end portion thereof. The horizontal swinging motion of the carriage 5 allows the magnetic head 3 to read and write data at any selected radial position on the magnetic disk 2.
The flexible wiring board 7, which is mounted on the carriage 5 to extend along the longitudinal direction thereof, is connected to the suspension substrate 4 mounted on the tip end portion of the carriage 5 and the control circuit substrate 6 disposed in proximity of the base end portion so that read/write signals from the control circuit substrate 6 can be transmitted to the magnetic head 3.
Shown in FIG. 8 is such a flexible wiring board 7 for connecting therethrough the suspension substrate 4 and the control circuit substrate 6. In FIG. 8, the flexible wiring board 7 is formed as a thin strap-like flat cable and a predetermined circuit pattern is formed in an insulating layer 8. Wires 9 are formed in the insulating layer 8 to extend in parallel along the longitudinal direction of the flexible wiring board 7. Suspension substrate side electrical contacts 10 to be connected with the suspension substrate 4 are formed in association with the respective wires 9 at one end of the wires 9. Control circuit substrate side electrical contacts 11 to be connected with the control circuit substrate 6 are formed in association with the respective wires 9 at the other ends of the wires 9.
When the flexible wiring board 7 is shipped and transported as merchandise, there sometimes arises the occasion that static electricity is generated in the flexible wiring board 7 by friction from vibrations and the like and is stored in the wires 9. If the flexible wiring board 7 in this condition is connected with the suspension substrate 4 having mounted thereon the magnetic head 3 at the assembly of the hard disk drive 1, there may arise a possible occasion that an unexpected voltage is applied to the magnetic head 3 due to an electric potential difference generated between the wires 9, to cause an electrostatic destruction of the magnetic head 3. In general, in order to prevent such an electrostatic destruction of the magnetic head 3, the wires 9 are bridged in advance through a shorting member so that electric potential between the wires 9 of the wiring can be equalized even when static electricity is generated during the shipment or transport. The shorting member bridging the wires 9 is cut off before use. To be more specific, in FIG. 8, the shorting member 12 bridges particularly two wires 9a and 9b, between which an electrostatic destruction of the magnetic head 3 may possibly be caused, by forming a soldering bump on each wire 9a, 9b and then flattening it out to bring those two wires into contact with each other. The shorting member 12 is cut off in the direction of arrows 13 before it is used for the assembly of the hard disk drive 1. It will be understood that the shorting member 12 may be formed with a wire interconnecting the wires 9.
However, when the shorting member is cut off before use, there arises a problem that chips of the solder or wire, i.e., conductive foreign materials, are produced and fly or run over the insulating layer to adhere to the magnetic head, and as such cannot ensure normal performance of the magnetic head.
Among others, the above-mentioned GMR head including delicate elements is low in dielectric strength and its normal performance may be hindered by even a small amount of foreign material.
To conform to high-performance and delicate magnetic heads which are being improved at an increasingly rapid rate in these years, development of a flexible wiring board that can allow the wires to be surely bridged to prevent the electrostatic destruction of the magnetic head and also can prevent production of conductive foreign materials involved in the cutting of the shorting member before use is now being anticipated.
It is the object of the present invention to provide a flexible wiring board that can surely bridge the wires and also can prevent production of conductive foreign materials in use, to secure good performance of the magnetic head.
The present invention is directed to a novel flexible wiring board for connecting therethrough a suspension substrate for mounting thereon a magnetic head of a hard disk drive and a control circuit substrate for actuating the magnetic head. The flexible wiring board of the present invention comprises a short-circuit forming portion for forming a shorting portion for bridging wires to prevent electrostatic destruction of the magnetic head; and a cut for removing the shorting portion.
With the flexible wiring board of the present invention thus arranged, the wires can surely be bridged, while also the shorting portion can be removed easily in use by simply cutting the flexible wiring board along the cut. Besides, since there is no need to cut off the shorting portion, as in the prior art, no conductive foreign material such as the chips of solder or wire is produced. As a result of this, the normal performance of the magnetic head is not hindered by such foreign material and therefore the good performance of the magnetic head can be well ensured.
Thus, the flexible wiring board of the present invention is effectively applicable to high-performance and delicate magnetic heads that are being improved at an increasingly rapid rate in these years.
It is preferable that the cut is formed so as to cut the flexible wiring board at a longitudinal part thereof.
With the arrangement in which the cut is formed so as to cut the flexible wiring board at a longitudinal part thereof, the shorting portion can easily be removed by simply folding the flexible wiring board at a longitudinal part thereof along the cut.
In addition, the cut is preferably formed in the form of a perforation bridging the wires in an insulating layer forming the wires therein.
With the arrangement in which the cut is formed in the form of a perforation, the flexible wiring board can surely and easily be cut along the perforation.
Also, the present invention provides a flexible wiring board for connecting therethrough a suspension substrate for mounting thereon a magnetic head of a hard disk drive and a control circuit substrate for actuating the magnetic head, the flexible wiring board comprising a suspension substrate side electrical contact forming portion, formed at one longitudinal end of the flexible wiring board, for connection with the suspension substrate; a control circuit substrate side electrical contact forming portion, formed in a longitudinal part of the flexible wiring board, for connection with the control circuit substrate; a short-circuit forming portion, formed at an outside of an area between the suspension substrate side electrical contact forming portion and the control circuit substrate side electrical contact forming portion with respect to a longitudinal direction of the flexible wiring board, for forming a shorting portion for bridging wires to prevent electrostatic destruction of the magnetic head; and a cut, formed between the control circuit substrate side electrical contact forming portion and the short-circuit forming portion, for removing the shorting portion.
Further, the present invention provides a flexible wiring board for connecting therethrough a suspension substrate for mounting thereon a magnetic head of a hard disk drive and a control circuit substrate for actuating the magnetic head, the flexible wiring board comprising a suspension substrate side electrical contact forming portion, formed at one longitudinal end of the flexible wiring board, for connection with the suspension substrate; a testing electrical contact forming portion, formed at the other longitudinal end of the flexible wiring board, for connection with a testing probe; a control circuit substrate side electrical contact forming portion, formed in a longitudinal part of the flexible wiring board, for connection with the control circuit substrate; a short-circuit forming portion, formed between the control circuit substrate side electrical contact forming portion and the testing electrical contact forming portion, for forming a shorting portion for bridging wires to prevent electrostatic destruction of the magnetic head; and a cut, formed between the control circuit substrate side electrical contact forming portion and the short-circuit forming portion, for removing the shorting portion.
According to the flexible wiring board of the present invention, the flexible wiring board can be divided into two parts i.e., a part to be used including the suspension substrate side electrical contact and the control circuit substrate side electrical contact and a part to be disused including the shorting portion and the testing electrical contact by simply cutting the flexible wiring board along the cut. This produces the result that the part to be disused including the shorting portion and the testing electrical contact which was already used for the testing can be removed at one time.